This invention relates to electrical connectors, and in particular, to contacts of connectors for leadless circuit boards such as leadless integrated circuit packages, leadless large-scaled circuit packages, and leadless printed circuit boards.
In order to removably mount the leadless circuit boards (which will be referred to as "daughter board") employing terminal pads in place of leads onto another circuit board (which will be referred to as "mother board"), connectors have been used in the prior art as disclosed in U.S. patent Nos. 3,904,262, 4,063,791 and 4,204,722. Generally speaking, such a connector includes a housing of insulator material for receiving the daughter board therein, a plurality of contact elements mounted in the housing to engage with terminal pads of the received daughter board and to connect with conductor elements of the mother board on which the connector is mounted, and clamping means for clamping and depressing the daughter board to the mother board to establish engagement between the terminal pads of daughter board and the contact elements and having hook members to engage with openings of connector housing to keep the daughter board in a depressed condition.
In an arrangement for fixedly mounting the connector on the mother board, each contact element is formed with a terminal pin portion downwardly extending from the housing, and the terminal pin portion is inserted into a corresponding aperture or through-hole formed in the corresponding conductor element of the mother board and is soldered thereto, so that the connector is fixedly mounted on the mother board as well as electrical connection of the contact element with the conductor element. In this arrangement, since no means for joining the housing per se to the mother board is required, volume of the connector housing and area required to mount the connector preferably reduced. However, in order to avoid such a bad mounting condition of the connector where the housing is maintained to be raised and spaced apart from the surface of the mother board, the connector is required to be pressed onto the surface of the mother board during soldering process. This means that the soldering process is performed manually not automatically.
Since the connector is fixedly mounted on the mother board by the contact elements, contact elements are required to be firmly joined to the hoursing. However, assembling and intended disassembling of the contact elements to the housing are required to be readily performed, for production and servicing.
Furthermore, in order to realize reliable engagement of contact elements with terminal pads of the daughter board received in the connector, it is desired that sufficient and uniform contact pressure is generated for reliable engagement between the contact elements and the terminal pads without any engagement of the daugther board with a portion other than the contact region of the contact element.